5.10 to 6.06 (Breezy to Dapper)

Before you start

I would recommend using clonezilla for backing up your current installation. It is very easy to backup and restore your partitions with clonezilla. It takes less then 30 minutes to backup/restore a 20Gb root filesystem which has 4-5 Gb used space.

The upgrade

Make sure your sources.list is correct

For the upgrade you only need this list, comment your original sources or remove them.

Reboot your machine and you can now run lsb_release -a to check the new version of Ubuntu.

Remove obsolete packages

sudo aptitude

Now you will enter aptitude in interactive mode, select Obsolete and locally installed packages menu and press '_', then press 'g'. It could be that you will get messages that aptitude wants to remove your current kernel, do NOT remove it, leave it, we can remove it later on.